Yea, there are a ton of limits to energy. Use too much in a confined spot and you lose your thermal gradient to do useful work. Use too much too long, and well you've turned your local universe into entropy. Put too much in one spot, you create a black hole.
One interesting thing about the human mind is, early in life it uses a huge portion of our total energy, somewhere around 60% of our total energy flux. Later in life it only uses around 20% of our total energy and it does this by taking a lot of shortcuts and reducing connectivity except to 'where it matters'. Of course this makes it much more difficult for us to learn new things at the same speed as when we were young, but as long as our environment doesn't change too much it allows us to conserve a ton of energy to survive lean times.
One interesting thing about the human mind is, early in life it uses a huge portion of our total energy, somewhere around 60% of our total energy flux. Later in life it only uses around 20% of our total energy and it does this by taking a lot of shortcuts and reducing connectivity except to 'where it matters'. Of course this makes it much more difficult for us to learn new things at the same speed as when we were young, but as long as our environment doesn't change too much it allows us to conserve a ton of energy to survive lean times.